Gift of a drink in an explosive case (6)
I believe the answer is:
talent
'gift' is the definition.
('talent' can be a synonym of 'gift')
'a drink in an explosive case' is the wordplay.
'a drink' becomes 'ale' (ale is a kind of drink).
'in' indicates putting letters inside.
'an explosive case' becomes 'tnt' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ale' going within 'tnt' is 'TALENT'.
'of' is the link.
Can you help me to learn more?
(Other definitions for talent that I've seen before include "money no longer usable" , "Special ability, flair" , "Natural endowment" , "able people" , "Special aptitude for the old Greek money" .)